The long-term goal of the program of research of which this proposal is part is the development of tobacco cessation programs targeted at light smokers at greatest risk for progressing to daily smoking. Recent evidence suggests the prevalence of light and intermittent smoking (LITS) has increased dramatically. LITS increases morbidity and mortality, and many intermittent smokers progress to riskier daily smoking. Little is known about factors that are associated with LITS, or that confers risk for transition to daily smoking, or promotes transition to non-smoking. With LITS, smoking behavior may be based on reinforcement rather than alleviation of withdrawal. Most cessation programs are based on a physical dependence model, and may therefore be less effective for non-daily smokers. LITS, as well as use of other nicotine and tobacco products, is most common in younger populations. This proposal is conceptually based in Social Cognitive Theory (SCT), which posits that behavioral decisions are determined by cognitive factors such as self-efficacy, outcome expectancies, and behavioral intentions; these are influenced by the social environment. We hypothesize that changes in smoking patterns will be associated with these constructs and how they change over time. The purpose of the proposed research is to: (1) longitudinally examine LITS stability versus transitions to daily and non-smoking; (2) to test whether the SCT model predicts the probability of smoking stage transitions, (3) to evaluate whether SCT effects are moderated by personality and environmental factors, and (4) to test the hypothesis that use of other nicotine and tobacco products potentiates the risk of progression from LITS to daily smoking. Our goal is to analyze which variables play a role in longitudinal smoking outcomes and to assess mechanisms that explain these effects. The proposed research will lead to a better understanding of mechanisms by which intermittent smokers become daily and non-smokers, and is consistent with President Obama's emphasis on prevention of negative health outcomes. These data may have important implications for prevention and treatment. By identifying risk and protective factors that promote transition to daily and non-smoking, we hope to lay the groundwork for the development of interventions that explicitly target intermittent smokers and their smoking motives.